New research on survivors of the Holocaust shows how catastrophic events can alter our body chemistry, and how these changes can transmit to the next generation. The result? Our children may suffer the effects of a traumatic event they never witnessed. NewsHour’s Stephen Fee has the story.

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STEPHEN FEE:

Fifty-nine-year-old Karen Sonneberg grew up on the North Shore of Long Island, just an hour's drive from New York City. Her parents survived the Holocaust but rarely mentioned it.

KAREN SONNEBERG:

"All I knew was that we were different, that I was different. I didn't exactly know why."

STEPHEN FEE:

Her parents were Jewish, born in Germany – but after Hitler came to power, their families fled. Sonneberg's parents were just children but carried the traumas of Nazi oppression throughout their lives.

KAREN SONNEBERG:

My mother from the time she was three on, For my father, from the time he was five or six-years-old, he was subjected to the painful existence in Germany."

STEPHEN FEE:

Despite her own comfortable upbringing here in the US, Sonneberg privately struggled for years with anxiety and stress. While she couldn't prove it, she believed it was somehow linked to her parents' traumatic childhoods.

KAREN SONNEBERG:

"Having discussed this with many of my friends who come from similar backgrounds, it seems to be consistent in most of us, or we've had the same challenges. There were definitely challenges that quote unquote 'American' kids didn't seem to have experienced."

STEPHEN FEE:

"Even though you weren't there."

KAREN SONNEBERG:

"Exactly. That's the amazing part of it."

STEPHEN FEE:

Now, a new study published this month in the scientific journal Biological Psychiatry, bolsters Sonneberg's belief that she experienced the after effects of her parents' trauma.

Dr. Rachel Yehuda, director of Mount Sinai's Traumatic Stress Studies Division led the study. Her team interviewed and drew blood from 32 sets of survivors and their children, focusing on a gene called FKBP5

RACHEL YEHUDA, ICAHN SCHOOL OF MEDICINE AT MT. SINAI:

"We already know that this is a gene that contributes to risk for depression and Post-Traumatic Stress Disorder."

STEPHEN FEE:

Yehuda noticed a pattern among the Holocaust survivors called an "epigenetic change" — not a change in the gene itself, but rather a change in a chemical marker attached to it.

RACHEL YEHUDA, ICAHN SCHOOL OF MEDICINE AT MT. SINAI:

"When we looked at their own children, their children also had an epigenetic change in the same spot on a stress-related gene."

STEPHEN FEE:

"What does that suggest?"

RACHEL YEHUDA, ICAHN SCHOOL OF MEDICINE AT MT. SINAI:

"Well, in the first generation, in the Holocaust survivor, it suggests that there has been an adaptation or a response to a horrendous environmental event, and in the second generation it suggests that there has also been a response of the offspring to this parental trauma."

STEPHEN FEE:

Which means children of Holocaust survivors like Sonneberg could be more likely to develop stress or anxiety disorders.

Though their study was small, Yehuda and her team controlled for any early trauma the survivors' children may have experienced themselves.

STEPHEN FEE:

"How is it that a parent who was subjected to the trauma of the Holocaust is able to somehow transmit that to a child who wasn't there?"

RACHEL YEHUDA, ICAHN SCHOOL OF MEDICINE AT MT. SINAI:

"That's a really good question, and this study that we did doesn't address 'the how.' The study that we did just provides a proof of concept that we might be able to identify the how if we do more research."

STEPHEN FEE:

DNA is passed from parents to children. But research like Yehuda's suggests parental life experiences can modify their body chemistry — and those modifications can be transmitted to children as well.

Scientists have examined this idea before. After a famine in Holland during 1944 and 1945, children were born with the effects of malnutrition two generations after the food shortage ended.

Previously, Yehuda herself studied stress hormone levels in children born to women who survived the September 11th terrorist attacks. She's been examining the link between trauma experienced by Holocaust survivors and their children for more than 20 years.

RACHEL YEHUDA, ICAHN SCHOOL OF MEDICINE AT MT. SINAI:

"A trauma is an event that changes you. It doesn't have to change you for the negative. Trauma changes you in lots of different ways, but most people who experience extreme trauma learn a great deal from that experience, and some of those lessons may be lessons that are transmitted to the child, and that's not a bad thing."

STEPHEN FEE:

Yehuda says the implications aren't limited to Holocaust survivors. But this dwindling population provides insight into how clinicians understand and treat stress disorders.

RACHEL YEHUDA, ICAHN SCHOOL OF MEDICINE AT MT. SINAI:

"If you're at risk for heart disease, a lot of times the doctor can separate out well this is your weight, that's not good, this is your diet, these are you genetic risks, and things like that. And it would be very nice if we could develop a similar risk profile in the mental health arena where we would be able to understand where the risk factors come from for depression and anxiety."

STEPHEN FEE:

"We're on the tenth anniversary of Hurricane Katrina. There were children who were born after that trauma. There are children born in the trauma of a war in Syria and other crises around the world. If you're the child of a parent who experienced trauma, are you doomed to be depressed or stressed for the rest of your life?"

RACHEL YEHUDA, ICAHN SCHOOL OF MEDICINE AT MT. SINAI:

"I don't think you're doomed. But I think that many children of traumatized parents have struggled with depression and anxiety. And I can tell you that many of them have felt relieved that there might be a contributing factor that has been based on how they're responding to their parental trauma. I think that it's helped people work through a lot of that depression and anxiety."

STEPHEN FEE:

Relief is exactly what Karen Sonneberg, the child of Holocaust survivors, felt after she participated in one of Dr. Yehuda's trauma survivor studies. She lost her mother 30 years ago but looks forward to her father's 90th birthday next year.

KAREN SONNEBERG:

"I learned to cope in my life. I've learned to move on and get over all of this. Had I known at the time how my reactions could impact future children, my children's reactions, I might've dealt with things differently or gotten them some sort of treatment that maybe would help them in the future."